240sd

I have a 1991 240sx fastback, Automatic Transmission w/ 250k miles. She is currently not starting, but she turns over fine. I pulle the ecu code: 34 also='s KNOCK sensor. I reset ecu, and pull the code again. Now its suppose to be cleared as It read code: 55.
After it reads 55, I took the key out of the ign....then try to start....Nothing. Same results, she just turns over and no fire.
This is the 4th time it has been not starting. 1st, a month ago when the rain first came in. Along with driving with a low gas tank. One morning, I pulled her up to the driveway to load a PC.monitor in the trunk. After quick loading, I went to start her up...CRANK.CRANK.CRANK......-----After many cranks and 1gallon of gasoline added just to elimate the empty tank. Still just only cranks...I kept at it for a half-hour or so....I notice the fuel pump was not priming with the key in the ON position. So I kept turning key on and off. Now with the gas pedal depress a little there seem to be a buzzing sound from engine bay or underneath the vehicle(tranny)???
Soon after the buzzing noise I started cranking with the foot on gas technic *5-10mins**she responded, but it was really hard to start. I had to rev her up while cranking. She basically wanted to die.....
The next evening, same rainy weather. Same result, after a 40min drive. Lounged for 2hrs and when I left my friends house. She just would not start. This time I had at least 1/4 tank of gas. So I end up killing the battery Cranking (long cranks) At this point I added 1gallon of gas, but it was no use even with jump starting with my friends car....((((I have an A/T))
I abandon her for a week, and did some online searching..........1.5hrs , after checking for sparks, -orange/yellow sparks....Plugs seem to be fine.
I though I figured her out after unplugging the Battery and stepping on the brakes for 5mins then reconnected the neg-battery connector....FLAMES!!!!!!!she fired right up on the first crank. WOW!!

After that she ran for a 5weeks/ 1300miles. Then last week, again with the low fuel tank when I got home. The next morning, She only cranks.....
This time the battery / dis-reconnect did not work...so I pulled out the ECU and tried reseting it that way......Code read #34....I reset it and same results....after #34 and reset then #55..reset. Key out of ignition...Went to start her up====No Cigar...........I gave up....and went to dinner......and 2hrs later....before I went upstairs I jump in her and I notice the fuel pump...Then I knew she was going to Fire.......she bogg and fired up just like the original time it happened.....Rev her up for a 20min drive....parked the next day....I went to return my pops pickup and on the way home I picked up some grocery....30mins later....I came out and start her up. She fired and RPM@ 400max.....Bogging and trying to start.....As soon as I tapped the gas and try to rev her up. She dies automatically.....Doing this for 5mins and then she only cranks now like before......Now when she turns over, it seem the car shakes more roughly........That is where she sits.
fuel pump fuse is15a and is okay, oem is 10a , will that cause problem. the relays are are loose too......

Thank you for looking. Someone please help.


My thoughts were that code:#34 knock sensor, = FAIL SAFE MODE?
Causing the fuel pump cut out and not allow fuel prime
Grounding issue??
Distributor/crank angle sensor???

240sd

what exactly was your problem??? Were you not getting fuel presure or fuel pump priming with the ignition on...I was thinking I need a new fuel pump or fuel pump relay???
let me know what your problem was so I can check it out with the o2 sensor....Thanks for the reply....

Nismo1

sounds to me like your fuel pump is a prime suspect....giving it gas while cranking is fine, be sure to take it easy or you will cause it to flood.....if its cranking every time then your starter sounds fine, ..check all the sensors, but before you check the sensors, make sure you disconnect the neg. terminal from the battery, if not the sensor will not reset